A dual-period response of the Kuroshio Extension SST to Aleutian Low activity in the winter season  

作　　者：YU Peilong ZHANG Lifeng LIU Hu LIU Xing ZHU Juan 

机构地区：[1]College of Meteorology and Oceanography, National University of Defense Technology, Nanjing 211101, China [2]No.61741 Troops of PLA, Beijing 100025, China [3]Maritime Environment Project Office, Beijing 100081, China

出　　处：《Acta Oceanologica Sinica》2017年第9期1-9,共9页海洋学报（英文版）

基　　金：The National Basic Research Program(973 Program) of China under contract No.2013CB956203;the National Natural Science Foundation of China under contract No.41375063;the Junior Fellowships for CAST Advanced Innovation Think-tank Program under contract No.DXB-ZKQN-2016-019

摘　　要：Based on our previous work, the winter sea surface temperature（SST） in the Kuroshio Extension（KE） region showed significant variability over the past century with periods of ~6 a between 1930 and 1950 and ~10 a between1980 and 2009. How the activity of the Aleutian Low（AL） induces this dual-period variability over the two different timespans is further investigated here. For the ~6 a periodicity during 1930–1950, negative wind stress curl（WSC）anomalies in the central subtropical Pacific associated with an intensified AL generate positive sea surface height（SSH） anomalies. When these wind-induced SSH anomalies propagate westwards to the east of Taiwan, China two years later, positive velocity anomalies appear around the Kuroshio to the east of Taiwan and then the mean advection via this current of velocity anomalies leads to a strengthened KE jet and thus an increase in the KE SST one year later. For the ~10 a periodicity during 1980–2009, a negative North Pacific Oscillation-like dipole takes2–3 a to develop into a significant positive North Pacific Oscillation-like dipole, and this process corresponds to the northward shift of the AL. Negative WSC anomalies associated with this AL activity in the central North Pacific are able to induce the positive SSH anomalies. These oceanic signals then propagate westward into the KE region after 2–3 a, favoring a northward shift of the KE jet, thus leading to the warming of the KE SST. The feedbacks of the KE SST anomaly on the AL forcing are both negative for these two periodicities. These results suggest that the dual-period KE SST variability can be generated by the two-way KE-SST-AL coupling.Based on our previous work, the winter sea surface temperature（SST） in the Kuroshio Extension（KE） region showed significant variability over the past century with periods of ~6 a between 1930 and 1950 and ~10 a between1980 and 2009. How the activity of the Aleutian Low（AL） induces this dual-period variability over the two different timespans is further investigated here. For the ~6 a periodicity during 1930–1950, negative wind stress curl（WSC）anomalies in the central subtropical Pacific associated with an intensified AL generate positive sea surface height（SSH） anomalies. When these wind-induced SSH anomalies propagate westwards to the east of Taiwan, China two years later, positive velocity anomalies appear around the Kuroshio to the east of Taiwan and then the mean advection via this current of velocity anomalies leads to a strengthened KE jet and thus an increase in the KE SST one year later. For the ~10 a periodicity during 1980–2009, a negative North Pacific Oscillation-like dipole takes2–3 a to develop into a significant positive North Pacific Oscillation-like dipole, and this process corresponds to the northward shift of the AL. Negative WSC anomalies associated with this AL activity in the central North Pacific are able to induce the positive SSH anomalies. These oceanic signals then propagate westward into the KE region after 2–3 a, favoring a northward shift of the KE jet, thus leading to the warming of the KE SST. The feedbacks of the KE SST anomaly on the AL forcing are both negative for these two periodicities. These results suggest that the dual-period KE SST variability can be generated by the two-way KE-SST-AL coupling.

关 键 词：sea surface temperature Kuroshio Extension Aleutian Low activity dual-period variability 

分 类 号：P731[天文地球—海洋科学]